import java.util.Scanner;

public class B127 {
	public static int recursionDivine(int n) {
		if(n == 1 || n == 0)
			return 1;
		else
			return recursionDivine(n - 1) + recursionDivine(n - 2);
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n;
		
		while(sc.hasNext()) {
			n = Integer.parseInt(sc.nextLine());
			
			System.out.println(recursionDivine(n));
		}
	}
}